In non-extinct species, the avian egg is known to range in mass from 0.25 to 1,500 grams. The common poultry egg has an average weight of about 60 grams. The common fertilized poultry egg is both self-contained life support system and cradle. However, the life support system is flawed. It lacks oxygen. All other elements are present, including the fuel with which the fire of life will be sustained through the twenty-one day journey.
Oxygen is the driving force which feeds the biological matrix from which the new life is fashioned. The cycle of synthesis begins at the moment "set" occurs, i.e. the moment that the process of viability is initiated when the temperature of the fertilized egg exceeds about 68.degree. F. to about 70.degree. F. for any substantial period of time.
From the first moment the process of viability begins, the margins of success are tenuous. A race between catabolic and anabolic processes is initiated as life force courses forward. Oxygen must be obtained and the apparatus for gathering it must be fashioned within the margins of the small reserves available. Never again will the challenge be quite so great or the margins so small. The slightest unfavorable environmental conditions, and the battle is lost.
Unfortunately, the optimal conditions for incubation also favor internal competitive breakdown forces and external invasive ones. Ideal conditions in the incubator, darkness, moderately high humidity and temperatures of 99.5.degree. F..+-.0.5.degree. F. are nearly optimal for microbial life which will proliferate around and inside the egg shell. Thus, a multitude of foreign life forms are present. Some may be innocuous, others competitors or antagonists, and it is even possible that some familiar types such as Salmonella are symbiotic to the avian neonate.
The viability processes begin at the center but are subsequently focused outward to the extremities of the egg. Surrounding the embryo is a laminar set of membranes. The outermost layer (actually, a bi-layer) lies against the shell. The innermost layer is referred to as the chorioallantoic membrane and envelopes the albumen and yolk.
The outer shell is made up of crystalline calcium and is many times thicker than the inner shell and other adjacent membranes combined. The external surface has trumpet-shaped pores which run through the shell to the surface to the membrane. Typically, there are about 7,000 to 17,000 pores distributed over the shell surface, the highest density being at the rounded end (top) of the egg proximal to the air sac located adjacent to the interior of the shell. The air sac is a space created by a parting between the outer and inner shell membranes wherein the outer membrane remains attached and the inner (chorioallantoic) membrane is detached from the outer shell membrane. The separation between the two membranes creates the air sac which serves as a gas exchange depot, sometimes referred to as the "dumb" lung. The dumb lung respires in response to changes in temperature and atmospheric pressures. The dumb lung also grows larger and larger as the ovum takes up less and less space in using up its reserves, the byproducts of which pass through the lung to the outside. Once incubation has started, the embryo provides a network of arteries and veins to the working side of the lung, which thereafter allows for efficient gas exchange through the lung.
Prior art teaches that as pressure is applied and then increased to fertilized eggs, fatalities from the onset of pressure very quickly increase to 100%. Prior art also teaches that as vacuum is applied and then increased to fertilized eggs, fatalities from the onset of pressure very quickly increase to 100%. Furthermore, prior art shows that when ambient oxygen is increased or decreased above normal concentrations (21%) during incubation, the hatch rate of fertilized eggs decreases markedly. In sum, prior art shows that there is no known advantage to any process applied to fertilized eggs prior to incubation, and that fertilized eggs are adversely affected by such treatments.
Handling and artificial incubation methods have developed over the last century to create the best known conditions of humidity, air circulation, stable storage and incubation temperatures, and motion to provide maximum hatch of fertilized egg stock. For storage of fertilized egg stock, air sac (top) up for no longer than twenty days at a temperature of about 55.degree. F. is preferred. For incubation, air sac (top) up, humidity of about 60% during the first 18 days and about of 70% the last three days, a temperature of 99.5.degree. F. .+-.0.5.degree. F. with a gentle, cradle-like rocking motion, timed about once every ninety minutes, and filtered, recirculated ambient air (21% O.sub.2) is preferred. These conditions result in more or less maximum average hatches. Percentages of average hatches vary considerably depending upon the storage age of fertilized egg stock and the age, type and conditions of laying flocks from which they are derived. In general, the range is from about 80% to under 86% hatch, or a 14% to 20% mortality less the percentage of unfertilized eggs.
Shortly after hatching, chicks are injected with vaccines (such as Marek's) to prevent flock diseases. Significant expense and mortality are incurred due to the invasive nature of the injection.
Improvements in the overall healthiness of the hatched chicks strongly influences efficiencies with respect to grow-out factors of the flock, i.e., percentages of grow-out mortality, size, strength, fertility, feed conversion, susceptibility to disease and, ultimately, overall commercial success of the flock as layers, breeders or broilers and fryers for meat. Improvements related to better disease resistance, feed conversion, strength and increased commercial success from grow-out are also desirable. Finally, the ability to provide early nutritional advantages, to provide medications related to improved mortality or growth, to alter or manipulate sex characteristics, to provide microbial synergists (probiotics), to control disease agents, including those of poultry and those pathogenic to humans, is also desirable.